There are many advantages to tansmitting light energy via optical fiber waveguides and the use thereof is diverse. Single or multiple fiber wave guides may be used simply for transmitting light to a remote location. Complex communication systems may transmit multiple specific optical signals. These devices often require the coupling of fibers in end-to-end relationship. The coupling is a source of light loss with axial misalignment representing a particularly serious problem. Other factors causing signal loss are angular misalignment of fibers, longitudinal separation of fiber ends and reflection or refraction at the fiber ends.
In response to the need to efficiently couple separate optical fibers, various approaches have evolved. U.S. Pat. No. 4,257,674, "Elastomeric Splice", to Griffin et al., is directed to a splice or holder fabricated from an elastomeric material. The substantially cylindrical splice exhibits an axially aligned opening characterized by a diameter smaller than the diameter of the optical fiber. As a fiber is inserted into the opening, the walls of the splice tend to expand. Elastomeric restoring forces exerted on the fiber tend to maintain proper axial alignment. In a preferred embodiment, the axial aligned opening exhibits a triangular cross-section so that contact is made and restoring force applied to the fiber at three points on its circular cross-section.
U.S. patent application Ser. No. 112,991, entitled "Optical Fiber Connector" by W. John Carlsen, (now abandoned) describes an optical fiber connector utilizing the fiber holder described above. The connector body is molded from an optical quality plastic and comprises a convex lens recessed a predetermined distance from a reference surface. A second surface, parallel to the reference surface, has a point displaced approximately one focal length from the lens and defines a focal plane for the lens. The connector body has a substantially cylindrical cavity into which the fiber holder is inserted. In operation, an optical fiber is inserted into the axial opening in the holder until it abuts the second surface. Light emanating from the end of the fiber diverges and propogates approximately one focal length, where it impinges on the molded lens. The molded lens effectively collimates the divergent optical beam into a parallel beam.
Clearly such a connector system comprising back-to-back connectors, each including a fiber holder and lens assembly, represents a substantial advance in heretofore known techniques for coupling optical signals from one fiber to another. A primary advantage of the collimating, or expanded beam, lens connector is its relative immunity to axial misalignment or lateral separation of the optical fibers.
The subject invention is directed to a drawer connector assembly, the assembly designed to accommodate a spring-loaded and expanded beam lens, as described above.
The drawer connector assembly is designed to be readily field installable and requires no critical length gauging of the optical fibers. The assembly affords enhanced flexibility inasmuch as individual plug and receptacles may be interchanged without reconnection of the optical fiber. The invention accepts optical fibers of varying diameters while limiting the insertion loss of mated pairs to 1.0 db.